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Last Updated: Monday, 28 February 2005, 12:15 GMT
Newest Saturn moons given names
Image: Nasa/JPL/SSI
S/2004 S1 and S2 were discovered in August
Three new moons discovered around Saturn by the Cassini spacecraft have been given provisional names.

The discoveries were made last year, not long after Cassini had arrived in orbit around the ringed planet.

Two moons detected in August have been given the names Methone and Pallene, while another found in October has been provisionally named Polydeuces.

Three more candidate objects are still awaiting confirmation as moons.

Methone and Pallene circle Saturn between the orbits of two other Saturnian moons, Mimas and Enceladus.

Polydeuces is an example of a so-called Trojan moon - it is twinned with a larger satellite in orbit around the planet.

Wandering moon

Trojan moons are found near stable "Lagrange points" - places where the gravitational pull of the planet and the larger satellite become balanced.

The Trojans are situated 60 degrees ahead or behind the larger moon in its orbit (in the case of Polydeuces, the larger moon is Dione).

"Unlike Helene, Dione's other Trojan moon, Polydeuces can get as close as 39 degrees to Dione and then drift as far as 92 degrees from it, taking over two years to complete its journey around the Lagrange point," commented Cassini Imaging Team member Professor Carl Murray, from Queen Mary, University of London, UK.

"The extent of this wandering is the largest detected so far for any Trojan moon."

Two objects seen in June called S/2004 S3 and S/2004 S4 are still awaiting confirmation as moons. Another candidate moon - S/2004 S6 - was seen in October.

Professor Murray explained that although S/2004 S4 had not been seen since, S3 was seen again in October.

"If it has survived for that long, chances are that it is a moon. But then again, there are pictures where we would have expected to see it and didn't," he said.

He added that the Cassini Imaging Science Team was hoping to see the object again to confirm that it was a moon.

The Cassini spacecraft arrived at Saturn in July 2004, and put the Huygens probe on the moon Titan on 14 January, 2005.

The $3.2bn Cassini-Huygens mission to Saturn and its satellites is a joint venture between the US space agency (Nasa), the European Space Agency (Esa) and the Italian Space Agency (Asi).

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